Remove RenderFlowThread::offsetFromLogicalTopOfFirstRegion().

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index 388b83a670e0fe316b9e2337f7bbc50495b45559..7293b6b0f35cd6c5ff961b948dbba0d4a0ed0f4b 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -3645,22 +3645,14 @@ void RenderBlock::updateMinimumPageHeight(LayoutUnit offset, LayoutUnit minHeigh
 LayoutUnit RenderBlock::offsetFromLogicalTopOfFirstPage() const
 {
     LayoutState* layoutState = view()->layoutState();
-    if (layoutState && !layoutState->isPaginated())
-        return 0;
-
-    RenderFlowThread* flowThread = flowThreadContainingBlock();
-    if (flowThread)
-        return flowThread->offsetFromLogicalTopOfFirstRegion(this);
-
-    if (layoutState) {
-        ASSERT(layoutState->renderer() == this);
-
-        LayoutSize offsetDelta = layoutState->layoutOffset() - layoutState->pageOffset();
-        return isHorizontalWritingMode() ? offsetDelta.height() : offsetDelta.width();
-    }
-
-    ASSERT_NOT_REACHED();
-    return 0;
+    RELEASE_ASSERT(layoutState);
+    if (!layoutState->isPaginated())
+        return LayoutUnit();
+    // It would be possible to remove the requirement that this block be the one currently being
+    // laid out, but nobody needs that at the moment.
+    ASSERT(layoutState->renderer() == this);
+    LayoutSize offsetDelta = layoutState->layoutOffset() - layoutState->pageOffset();
+    return isHorizontalWritingMode() ? offsetDelta.height() : offsetDelta.width();
 }
 
 LayoutUnit RenderBlock::collapsedMarginBeforeForChild(const RenderBox& child) const